| 摘要 |
<p>913,738. Monogrammic signs. SYLVANIATHORN COLOUR TELEVISION LABORATORIES Ltd. Jan. 26, 1961 [Feb. 5, 1960], No. 4245/60. Class 118. [Also in Groups XXXVI, XL (a) and XL (b)] A resonant body of piezo-electric material is employed in conjunction with an electroluminescent element to provide a frequencysensitive light emitting device. In Fig. 1, an elongated block of piezo-electric material 10, which may be quartz or a ceramic containing barium titanate or lead zirconate, is provided at one end with a metallic conductor 11 and at the other with a layer 12 of electro-luminescent material on which is placed a glass plate 13 coated on its underside with a transparent conducting film 14, for example of stannic oxide. In an alternative construction, a mixture of electro-luminescent powder and glass frit is sintered on to the top of material 10 and sprayed with stannic chloride whilst hot. The most probable equivalent circuit is as shown in Fig. 2, where 18 represents the piezoelectric element, 19 the stray capacitance, and 12 the lossy capacitance formed by the electroluminescent layer. An alternating voltage of 50 volts at the series resonant frequency of the system generates 200 or more volts across layer 12 and causes the emission of light. Fig. 5 shows the construction of a two-dimensional array of devices in which a block of quartz tapering from its lower edge 29 to its upper edge 28 is cut (in a manner similar to Fig. 2), with slots 30, 31 so as to form a series of sections increasing in means length in the sequence 35, 36 ... 37, 38, &c. Electric connections and electro-luminescent layers are provided as described with reference to Fig. 1. The arrangement may be employed as a display panel in which a desired pattern of electroluminescent elements is illuminated by applying a signal having components of appropriate frequency. Specification 233,746 is referred to.</p> |
